staging: lustre: obdclass: don't require lct_owner to be non-NULL.

Some places in lu_object.c allow lct_owner to be NULL, implying
that the code is built in to the kernel (not a module), but
two places don't.  This prevents us from building lustre into
the kernel.

So remove the requirement and always allow lct_owner to be NULL.

This requires removing an "assert" that the module count is positive,
but this is redundant as module_put() already does the necessary test.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>